After Israel’s sin, when the people had turned away from God to worship the golden calf, God hears Moses’ prayer of intercession and agrees to walk in the midst of an unfaithful people, thus demonstrating his love. When Moses asks to see his glory, God responds “I will make all my goodness pass before you, and will proclaim before you my name “the LORD” [YHWH].”Then the LORD passes before Moses and proclaims, “YHWH,
YHWH, a God merciful and gracious, slow to anger, and abounding in steadfast love and faithfulness”; Moses then confesses that the LORD is a forgiving God.
The divine name, “I Am” or “He Is”, expresses God’s faithfulness: despite the faithlessness of men’s sin and the punishment it deserves, he keeps “steadfast love for thousands”. By going so far as to give up his own Son for us, God reveals that he is “rich in mercy”.By giving his life to free us from sin, Jesus reveals that he himself bears the divine name: “When you have lifted up the Son of man, then you will realize that “I AM”.
From the Catechism of the Catholic Church 210-211